/* vi: set tabstop=4 shiftwidth=4: */

/*
 * $Id: timing.c,v 1.2 1996/12/28 22:11:23 schweikh Exp $
 */

/*
 * functions for timing
 */

#include "config.h"
#include "error.h"
#include "timing.h"

#if HAVE_GETRUSAGE
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#else /* not HAVE_GETRUSAGE */
#include <time.h>
#endif /* not HAVE_GETRUSAGE */

/*
 * The cpu_usage() semantics are intended to be the same as of
 * clock() with the exception of returning seconds in a double
 * instead of clock ticks in a clock_t. If the system supports
 * getrusage, this function will be preferred over ANSI's clock()
 * because for example on systems where CLOCKS_PER_SEC is 1000000
 * clock() wraps after only 36 minutes (e.g. Solaris).
 */

double
cpu_usage (void)
{
#if HAVE_GETRUSAGE
  struct rusage res;

  check_sys (getrusage (RUSAGE_SELF, &res) == 0);
  return res.ru_utime.tv_sec + res.ru_utime.tv_usec / 1000000.0 +
    res.ru_stime.tv_sec + res.ru_stime.tv_usec / 1000000.0;
#else /* not HAVE_GETRUSAGE */
  return clock () / (double) CLOCKS_PER_SEC;
#endif /* not HAVE_GETRUSAGE */
}